devsw_detach_locked
static void devsw_detach_locked(const struct bdevsw *, const struct cdevsw *);
devsw_detach_locked(bdev, NULL);
devsw_detach_locked(bdev, cdev);
devsw_detach_locked(bdev, cdev);
devsw_detach_locked(bdev, cdev);